Apparatus for the collection of rainwater from a downpipe

ABSTRACT

A pipe of diameter significantly less than that of the downpipe is inserted up from the bottom of the downpipe and extends up the inside of the downpipe. The upper face of this inner tube is sealed so that water does not pour into its end. The wall of the inner tube is perforated so that water can flow into it from the sides as and when the downpipe fills with water to that level. The other end of this tube is in communication with the water butt allowing the water to flow from the downpipe to the water butt until the levels equalize or that in the downpipe falls below the level of said perforations.

RELATED APPLICATIONS

This application is the national stage entry of, and claims priority to,UK patent application serial number GB 1204979.7, titled “Apparatus forthe collection of rainwater from a downpipe”, and filed on Mar. 21,2012, the entire specification of which is hereby incorporated byreference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention pertains to water collection generally, and moreparticularly to collection of rainwater from building runoff.

2. Discussion of the State of the Art

Getting the rainwater from the roof on which it falls into a suitableholding tank can be achieved simply by placing a tank (also known as a“water butt” or, in the United States, a “rain barrel”) under the openend of a downpipe (or “downspout”) connected directly or indirectly tothe guttering around the roof. Water simply flows down the pipe and intothe barrel.

However, there are a number of disadvantages to this approach. Thelocation of the downpipe may not be a suitable site for a water butt.There may be several downpipes, each of which only catches a portion ofthe water required. Fitting the water butt under the downpipe oftenentails cutting off the lower portion of the downpipe. This requirestools, time and discourages temporary use of the pipe—especially incases where the person that wants to collect the water is not the ownerof the property or only wants a temporary solution. Someone renting abarn or stabling their horse at someone else's yard may not be allowedto cut a pipe in this way. There is also an issue with the overflow fromthe barrel. Ideally this should be piped back to the drain under thedownpipe through which the water would have run away had the water buttnot been installed. This can be tricky as the water butt itself may nowbe blocking the drain.

Hence “rainwater diverter” devices have been invented to intercept thewater within the downpipe and divert it to the water butt which can thenbe placed to one side of the downpipe. These typically require that thedownpipe is cut and the diverter inserted at the same height as theupper inlet to the water butt i.e. at the maximum height to which thewater butt will fill. Such devices normally take advantage of the factthat most of the water flows down the outside of the downpipe ratherthan through its centre. By trapping the falling water in an annularring with a lip of perhaps an inch in height, the water caught withinthat ring will flow out of a collection pipe in communication with theannular chamber thus formed and into the water butt at the other end ofthe collection pipe. Should the water butt fill to the level of thechamber, the water will no longer flow away to the water butt but willrise within the chamber until it overflows—with the excess water flowingdown through the open centre of the device and on down through the pipe.

Although such devices avoid the need to remove the bottom section of thepipe, they still require the pipe to be cut. This is particularlyproblematic in cast metal pipes. Furthermore, if the water butt issubsequently removed, the outlet from the diverter must be blocked orthe device removed and the two sections of pipe rejoined. Furthermore,the relatively small collection chamber accumulates debris washed downthe sides of the pipe. The small outlet to the collection pipe clogs upeasily due to leaves and other debris accumulating therein. Also, theheight at which the diverter is fitted must match the fill level of thewater butt or the overflow mechanism will not work. This level cannoteasily be adjusted once the pipe has been cut and the device inserted.So, for example, replacing the water butt with a larger, deeper one isnot an option. Furthermore, the collector typically only fits downpipesof a certain size.

The problem of dust and other debris collecting within water butts isitself a major problem. Several different approaches can be taken toachieve a “first flush filter”. When rain starts, the accumulated debrison the roof and in the gutters is washed downwards. The first few litresof water coming down the pipe in each shower contain a high proportionof this debris and are best not collected. A range of mechanisms havebeen designed to ensure that the initial few litres of water arediverted away from the collecting barrel. These include tilting guttermechanisms and containers with floating ball valves that collect thewater until full at which point the ball rises to the top, shutting themoff and diverting the subsequent water to the water butt. A smalldiameter outlet hole is often provided to allow their contents todribble slowly away, thus “resetting” them before the next shower.However, such devices also tend to collect debris—unsurprisingly—andneed to be cleaned out regularly. They also tend to take up more space,are rarely elegant additions to the outside of any property andtypically must be fitted in addition to the diverter mechanism ratherthan being an integral part of it.

There is therefore a need for a non-destructive, hidden mechanism forthe collection of water from downpipes. This would not force the waterbutt to be sited next to any particular downpipe. It would allowmultiple downpipes to feed a single water butt and, conversely, onedownpipe to feed several water butts—or any number of pipes to feed anynumber of water butts. It would not collect the first few litres in eachshower. It would avoid the accumulation of debris. It would ensure thatany overflow continued down the original route the water would havetaken prior to the device being fitted. It would be fitted andadjustable without the need for tools and without damage to thedownpipe. The invention described here achieves these goals byexploiting the fact that the downpipe itself is normally substantiallywatertight and can act as the first flush collector.

SUMMARY OF THE INVENTION

The invention is an apparatus that facilitates the collection ofrainwater flowing through a substantially vertical pipe such as adownspout from the eaves of a house. The bottom of the pipe issubstantially sealed so that a column of water accumulates in the pipewhen it rains. A perforated inner pipe, fed up from the bottom of thedownpipe, through said seal, allows this water to flow into a holdingtank such as a rain barrel.

In many parts of the world, water is scarce and becoming scarcer.Collection of rainwater is a valuable backup or alternative to mainswater supply. However, adding rainwater collection to an existingbuilding is sufficiently problematic that this valuable and freeresource is often allowed to go to waste.

The invention exploits the fact that most rainwater downpipes arethemselves hollow, watertight tubes that, if plugged or sealed at thebottom end, could hold a vertical column of water at least to theoverflow level of a connected water butt. The apparatus consists of abung or boot that can be affixed to the bottom of an existing downpipewithout having to cut or damage the downpipe. Nor does this requiresignificant space below the bottom of the downpipe. One or more ductspass through this end seal and project upwards into the existingdownpipe so as to allow water to be collected from a predeterminedheight within the watertight chamber thus formed from the bung or bootand the existing downpipe's walls.

A water collection pipe of diameter significantly less than that of thedownpipe itself is inserted up from the bottom of the downpipe andextends up the inside of the downpipe. The upper face of this collectionpipe is sealed so that water does not pour into its end. The wall of thecollection pipe is perforated for several centimeters beneath the sealedend so that water can flow into it from the sides as and when thedownpipe fills with water to that level. The other end of thiscollection pipe is connected (typically) to the bottom of the water buttallowing the water to flow from the downpipe to the water butt until thelevels equalize.

Preferably, an overflow mechanism is also provided such that if thewater level inside the downpipe exceeds the height to which the waterbutt can safely be filled, any excess water overflows down the drainabove which the downpipe is sited. This mechanism can take a number offorms—such as a float lifting a flapper-valve or a second, “overflow”pipe inserted into the downpipe. The overflow pipe is watertight up tothe overflow level but allows water to enter at or above this level.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The accompanying drawings illustrate several embodiments of theinvention and, together with the description, serve to explain theprinciples of the invention according to the embodiments. One skilled inthe art will recognize that the particular embodiments illustrated inthe drawings are merely exemplary, and are not intended to limit thescope of the present invention.

FIG. 1 shows an example of the apparatus using a float activatedoverflow valve installed in a downpipe and connected to a water butt.

FIG. 2 shows detail of exemplary perforations towards the upper end ofthe collection pipe of FIG. 1.

FIG. 3 shows an alternative implementation with no moving parts, using asecond tube to achieve the overflow mechanism.

FIG. 4 shows a plan view of the flexible rubber or silicone bung used inthe apparatus of FIG. 3.

FIG. 5 shows a variant of the apparatus of FIG. 3 in which a single tubewith an internal dividing wall is used for both overflow and collectionof water.

FIG. 6 shows how the apparatus of FIG. 3 can be constructed as anintegral part of a downpipe section as an alternative to adding it to anexisting downpipe.

FIG. 7 shows a horizontal cross-section of the downpipe of FIG. 6, a fewcentimeters above the base of the downpipe.

DETAILED DESCRIPTION

The inventor has conceived, and reduced to practice, an apparatus forthe collection of rainwater from a downpipe that addresses thechallenges and problems in the art outlined above. Various techniqueswill now be described in detail with reference to a few exampleembodiments thereof, as illustrated in the accompanying drawings. In thefollowing description, numerous specific details are set forth in orderto provide a thorough understanding of one or more aspects and/orfeatures described or referenced herein. However, it will be apparent toone skilled in the art, that one or more aspects and/or featuresdescribed or referenced herein may be practiced without some or all ofthese specific details. In other instances, well known process stepsand/or structures have not been described in detail in order to notobscure some of the aspects and/or features described or referenceherein.

One or more different inventions may be described in the presentapplication. Further, for one or more of the inventions describedherein, numerous alternative embodiments may be described; it should beunderstood that these are presented for illustrative purposes only. Thedescribed embodiments are not intended to be limiting in any sense. Oneor more of the inventions may be widely applicable to numerousembodiments, as is readily apparent from the disclosure. In general,embodiments are described in sufficient detail to enable those skilledin the art to practice one or more of the inventions, and it is to beunderstood that other embodiments may be utilized and that structural,logical, software, electrical and other changes may be made withoutdeparting from the scope of the particular inventions. Accordingly,those skilled in the art will recognize that one or more of theinventions may be practiced with various modifications and alterations.Particular features of one or more of the inventions may be describedwith reference to one or more particular embodiments or figures thatform a part of the present disclosure, and in which are shown, by way ofillustration, specific embodiments of one or more of the inventions. Itshould be understood, however, that such features are not limited tousage in the one or more particular embodiments or figures withreference to which they are described. The present disclosure is neithera literal description of all embodiments of one or more of theinventions nor a listing of features of one or more of the inventionsthat must be present in all embodiments.

Headings of sections provided in this patent application and the titleof this patent application are for convenience only, and are not to betaken as limiting the disclosure in any way.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Tothe contrary, a variety of optional components may be described toillustrate a wide variety of possible embodiments of one or more of theinventions and in order to more fully illustrate one or more aspects ofthe inventions. Similarly, although process steps, method steps,algorithms or the like may be described in a sequential order, suchprocesses, methods and algorithms may generally be configured to work inalternate orders, unless specifically stated to the contrary. In otherwords, any sequence or order of steps that may be described in thispatent application does not, in and of itself, indicate a requirementthat the steps be performed in that order. The steps of describedprocesses may be performed in any order practical. Further, some stepsmay be performed simultaneously despite being described or implied asoccurring non-simultaneously (e.g., because one step is described afterthe other step). Moreover, the illustration of a process by itsdepiction in a drawing does not imply that the illustrated process isexclusive of other variations and modifications thereto, does not implythat the illustrated process or any of its steps are necessary to one ormore of the invention(s), and does not imply that the illustratedprocess is preferred. Also, steps are generally described once perembodiment, but this does not mean they must occur once, or that theymay only occur once each time a process, method, or algorithm is carriedout or executed. Some steps may be omitted in some embodiments or someoccurrences, or some steps may be executed more than once in a givenembodiment or occurrence.

When a single device or article is described, it will be readilyapparent that more than one device or article may be used in place of asingle device or article. Similarly, where more than one device orarticle is described, it will be readily apparent that a single deviceor article may be used in place of the more than one device or article.

The functionality or the features of a device may be alternativelyembodied by one or more other devices that are not explicitly describedas having such functionality or features. Thus, other embodiments of oneor more of the inventions need not include the device itself.

Techniques and mechanisms described or referenced herein will sometimesbe described in singular form for clarity. However, it should be notedthat particular embodiments include multiple iterations of a techniqueor multiple instantiations of a mechanism unless noted otherwise.Process descriptions or blocks in figures should be understood asrepresenting modules, segments, or portions of code which include one ormore executable instructions for implementing specific logical functionsor steps in the process. Alternate implementations are included withinthe scope of embodiments of the present invention in which, for example,functions may be executed out of order from that shown or discussed,including substantially concurrently or in reverse order, depending onthe functionality involved, as would be understood by those havingordinary skill in the art.

DETAILED DESCRIPTION OF EMBODIMENTS

Several variants of the invention are described by way of example. Itwill be obvious to one of skill in the art that there are many otherways to achieve the features described.

FIGS. 1, 2, 3 and 5 show different examples of the invention insertedinto a lower end of a substantially vertical downpipe (1). Across-section through only the lower two meters or so of downpipe (1) isshown. The downpipe (1) typically extends for at least a further onemeter to the eaves of a building where it joins the guttering. The open,lower end of the downpipe may be horizontal (as in FIG. 1) or bentthrough an angle, typically of fort-five or ninety degrees (so as todirect water away from the wall to which it is typically affixed).

Prior to the installation of the apparatus, water flows down from theroof, through downpipe (1) and into drain (3) beneath it.

Following the installation of the invention, a transfer pipe (4) mayconnect the invention to a water butt, rain barrel, or any otherwatertight container (5) that is to be filled with said rainwater.Transfer pipe (4) is typically thin-walled, very flexible and connectedat or near ground level to the apparatus and to container (5). It doesnot matter that the center of the pipe rests on the ground even thoughthe ends are often connected a few centimetres above ground level.Transfer pipe (4) may be contiguous with a collection pipe (describedlater) or may be joined to the collection pipe via any suitableconnector. This detail is not shown in the diagrams.

Optionally, transfer pipe (4) does not connect directly to water butt(5) but, rather, passes through a low level inlet (9) via a watertightseal, joint or connector and is terminated in a non-return valve (10)such as a duck-bill valve inside water butt (5). Valve (10) allows waterto flow into container (5) when the water pressure in transfer pipe (4)exceeds that outside valve (10) but blocks the flow of water in theopposite direction, even if transfer pipe (4) is empty of water.

The valve may be a simple flapper valve or a duck-bill valve made of avery pliable material, such as low-density polyethylene (LDPE) so as topresent very little resistance to water flowing into the butt. Thiscomponent (10)—or some other type of non-return valve is needed only incases where the apparatus is not completely watertight (as discussedlater), and where transfer pipe (4) enters water butt (5) below overflowlevel (6).

Alternatively, transfer pipe (4) may enter water butt (5) through ahigher-level inlet (7) at or above overflow level (6). In this case,water will only start to flow into water butt (5) when the water columnretained in downpipe (1) reaches this level (6). Optionally, in thiscase, transfer pipe (4) may continue inside water butt (5) such that itsopen end is close to the bottom of water butt (5). This arrangementallows more water to be collected as, once flow has started, theresultant siphon action will drain the bulk of the water from downpipe(1) into water butt (5).

To make the diagrams clearer, the width of downpipe (1) has beenexaggerated relative to that of water butt (5) and the vertical heightcompressed between bottom of downpipe (1) and the top of water butt(5)—so as to show the detail within the bottom section of downpipe (1)more clearly. In other words, a real water butt (5) would typically bemuch wider and taller than it appears in these drawings—holding manymore times the volume of water than does this lower section of downpipe(1).

Water butt (5) may be immediately beside or some distance from downpipe(1). It may be on the same level as the ground (2) beneath downpipe (1),or sitting up on a stand so as to allow a tap to be placed nearer thebottom of barrel (5) yet still be above the height of a bucket orwatering can. The elevation of the bottom of barrel (5) relative to thelower end of downpipe (1) is of little importance. However, the upperfill level (6) above which barrel (5) would overflow through outlet hole(7) is important. This level generally should be above both the level ofthe bottom of downpipe (1) and the first flush level (8).

In this example, downpipe (1) is a simple vertical cylinder and istypically of circular, square or rectangular cross-section with wallsmade of plastic, iron, steel or concrete between 1 and 5 millimeters inthickness. However, downpipe (1) can be of any cross-section and couldbe at an angle. In this example the open outlet of the pipe, absent theinvention, is a horizontal face a few centimeters above ground level(2). The explanation below assumes a circular cross-section and verticalpipe by way of example only. As long as the pipe is not horizontal, theinvention can still work but requires a longer collection pipe to reachthe required first flush (8) and overflow (6) levels.

Similarly, by way of example only, let us assume that the water butt (5)is full when the water in it is 1.5 meters deep and that it is onapproximately the same level as the ground (2) beneath downpipe (1).Further, assume that there is typically 15 centimeters between theground and the bottom of downpipe (1). Downpipe (1) itself is typically68 mm in diameter and at least 3 meters high.

The invention consists of a cylindrical “boot” (11) which is clampedaround the lower end of downpipe (1) so as to from a largely watertightseal. This allows water falling down the pipe to accumulate insidedownpipe (1). This seal does not need to be tolerant of high pressure asthe pressure will never exceed the depth of water butt (5) (1.5 m inthis case), nor does it need to be perfect as any slight leakage willfall down through drain (3) in the same way that it did prior to theinvention being attached.

Boot (11) can be clamped around downpipe (1) using a compressiblewatertight O-ring (12) and held in place by a jubilee clip (13)tightened by hand using butterfly nut (14). Other means of attachmentare possible. For example, if downpipe (1) is designed to acceptpush-fit connection of a further section of downpipe (1), boot (11) maybe made compatible with this connection style. As is the case with someexisting rainwater diverters, it will be appreciated that a singledesign of boot, with appropriately stepped concentric profiles can beaffixed to pipes of several different cross sections (large circular,small circular and square for example).

In the center of the lower face of boot (11) is a (typically) circularhole (15) of only slightly smaller diameter than downpipe (1) itself.This hole (15) is normally blocked by a circular disc (16) of slightlylarger diameter than the hole (15). The outer lower edge of disc (16)and/or edge of hole (15) are covered in a washer of silicone or similarmaterial so as to provide a watertight seal when disc (16) sits overhole (15) under its own weight or, more tightly, when water is pushingdown on it from above. This type of seal is common in toilet cisterns,particularly in the United States (less so in the United Kingdom). Fromthe center of disc (16) a narrow axial rod (17) projects upwards forapproximately 50 mm. This rod is constrained to move within a verticalhollow cylindrical guide (18) of internal diameter slightly greater thanthat of rod (17). This allows disc (16) to move upwards by approximately25 mm when lifted by a force applied upwards through rod (17). Guidecylinder (18) is held centrally within boot (11) by, typically, three ormore narrow radial spokes (19) connecting it to the wall of boot (11).

In one side of boot (11) is a circular hole (22) with a central grooveholding a circular flexible rubber, silicone or similar flange (23).Flange (23) is of slightly narrower diameter than transfer pipe (4),which can therefore be pushed through flange (23) giving a substantiallythough not necessarily perfectly waterproof seal around this pipe.Optionally, transfer pipe (4) may have a corrugated outer surfaceallowing the material of flange (23) to locate between successivecorrugations providing a better seal than it would on a smooth pipe.

Inside boot (11), transfer pipe (4) may be bent through approximatelyninety degrees and either expands into or is connected to a (typically)larger diameter collection pipe (24) that passes through a collar (25)in the centre of boot (11) (and hence downpipe (1)). As with cylindricalguide (18) this collar (25) is held in the centre of boot (11) bytypically three or more thin radial spokes (26) connecting it to thewall of boot (11).

Collection pipe (24) projects up the downpipe to several centimetersabove the overflow level of water butt (6). As the pipe is flexible itwill, in practice, meander slightly but is stiff enough that it does notdouble over when pushed up downpipe (1). The top of collection pipe (24)is sealed (27) to prevent water entering through this end of pipe (1). Arounded cap with a slight overhang is preferably used so as not to catchon any internal joints in the walls of downpipe (1) as it is pushed uppipe (1), but also to shield the openings below it from water fallingdownwards into them. Below this seal (27), but above a “first-flushlevel” (8), the walls of the collection pipe (24) are perforated so asto allow any water surrounding the pipe to enter it. Preferably, theseperforations provide both a filtering mechanism (by being small butnumerous) and a deflection mechanism. For example, as shown in FIG. 2,each perforation can be produced by making two cuts (28), (29) forming anotch with the point at the bottom. Pushing the tip of flap (30) thusproduced outwards at the forms a “barb” that deflects any water anddebris running down the outside of the tube. Water rising aroundcollection tube (24) will easily flow into the tube through these holesbut water running down the tube will not.

Alternatively, larger holes may be made in the walls of the tube andthis section of tube wrapped in a porous material or fine mesh such asthat used in the filters within vehicle fuel tanks or swimming poolclearing nets. Either approach achieves the goal of filtering out largerpieces of debris which will therefore accumulate within the base ofdownpipe (1) rather than enter collection tube (24).

Whether using overhung perforations or a mesh filter, the fact that thissection of collection pipe (24) is typically 50 cm or more in lengthmeans that a large surface area can be provided—allowing easy passage ofsignificant volumes of water, even if some particulates become lodged inthe filter or perforations.

As collection pipe (24) is watertight below first flush level (8), whenrain begins to fall, the initial flush of water (containing the bulk ofthe dust and debris collected on the roof and gutters since the previousrain) collects in boot (11) and bottom of downpipe (1). On its waythere, very little water enters collection tube (24) due to the factthat the water tends to flow down the outside of downpipe (1) andoverhanging flaps (30) and overhanging seal (27) deflect it from theperforations beneath them. Only after the water level inside downpipe(1) rises above first flush level (8) does it start to enter collectionpipe (24).

Collection pipe (24) is connected via narrower-gauge transfer pipe (4)to the inside of water butt (5)—typically via a screw connector orjubilee clip to a male to male nipple that is screwed into in a hole (9)near the bottom of water butt (5) using rubber washers to provide awatertight seal. On the inside of the nipple, optionally a duck-billedvalve (10) is screwed or clamped.

If the water level in butt (5) is lower than first flush level (8),water will begin to flow down collection pipe (24), through transferpipe (4) and hole (9) in the side of butt (5) and (if present) throughlow differential pressure valve (10).

If the level of water in the butt is higher than first-flush level (8),water will continue to accumulate in downpipe (1) and collection pipe(24) but will not flow from it into butt (5) until the height of waterin downpipe (1) (and hence collection pipe (24) exceeds that in butt(5).

Thus as water continues to flow down downpipe (1) it will flow throughcollection pipe (24) and transfer pipe (4) into butt (5), with the waterlevel inside downpipe (1) exceeding that in butt (5) by the small amountneeded to open valve (10).

When water butt (5) is full to overflow level (6), the invention ensuresthat any further water coming down downpipe (1) is released down drain(3), thus avoiding any problems with overflow at water butt (5) itselfand the consequent need to pipe water away from the top (7) of butt (5)to the nearest drain—typically the one (3) away from which the water hasjust been diverted in the first place.

The overflow mechanism in FIG. 1 is achieved by means of a hollowcylindrical float (21) inside the upper, perforated end of thecollection pipe (24). This is of slightly smaller diameter than theinside of collection pipe (24) and is blocked from falling down the tubeby a constriction or obstruction such as a pair of pins (31) or wirespushed through the walls of the pipe at right angles to each other. Asthe water level inside downpipe (1) reaches the maximum required, thisfloat will start to rise until it is blocked—just a few centimetershigher by sealed end (27) of the pipe. The small gap between obstruction(31) and top seal (27) is typically only 25 mm or so greater than theheight of float (21) so the float can only move up and down by thisamount.

A strong, lightweight smooth cord (20)—such as fishing line—is affixedto a lower end of float (21). This has been threaded through the wall ofcollection pipe (24) via a small hole not much wider than the cord (20)itself, ideally in the bend of the pipe directly above the center column(17) of lift-check valve (16). Cord (20) is threaded through a tinyaxial hole in the center of rod (17) and appears out the bottom of disc(16). There, a clip (32) grips cord (20) tightly—so that when float (21)pulls upwards on cord (20), clip (32) stops it from being pulled backthrough the hole in disc (16) and instead forces disk (16) to rise,opening hole (15) and allowing water to flow out and down drain (3) asit would have done in the absence of the invention.

As water leave downpipe (1), float (21) drops down again, letting valve(16) reseat, shutting off the flow of water. As water continues to enterthe top of downpipe (1), float (21) and attached valve (16) keep thewater level close to this maximum level.

As collection pipe (24) is typically less than half the diameter ofdownpipe (1), and valve (16) at the bottom lifts 25 mm above hole (15),water can flow through downpipe (1) at almost the same rate it couldprior to the invention being installed. As the peak flow rate istypically determined by that of the (gently inclined) gutters feedingdownpipe (1) rather than downpipe (1) itself, the overflow path can thusbe designed to cope with storm flow rates as well as the gutters do.

Note that this overflow mechanism will typically only be operated a fewtimes a year—during the heaviest rain storms (when the rate of inflow ofwater through the top of downpipe (1) exceeds the rate at which it canflow out to water butt (5) via pipe (4) and also when water butt (5) isalready full. In either case, the overflow starts only once the head ofwater inside downpipe (1) reaches preset overflow level (6). There istherefore typically 1.5 m head of water pushing the bottom of the columnof water out through valve (16). This rush of water helps toautomatically clean out any debris that has gathered in the bottom ofdownpipe (1) since the previous overflow incident.

However, there is still a chance that debris accumulates above valve(16) and eventually stops it from being lifted and/or openingeffectively. Although it is possible to push valve (16) up by insertingones fingers into hole (15) and teasing out leaves, dirt etc. this maybe insufficient to clear larger debris. The apparatus may be temporarilyremoved by loosening the butterfly nut (14), dropping boot (11) andattached components so that debris can be removed via the now exposedtop of the boot.

Alternatively, an access door, typically 50 mm high and extending for120 degrees or so around the upper edge of boot (11) can be provided.This is typically hinged at one end and snap-fit at the other end orsnap-fit at both ends. A rubber grommet inset around the edge of thistrap door provides a sufficiently watertight seal when the door isclosed. Projecting tabs over the snap-fit end(s) allow a user to pop thedoor open, insert a hand or tool to remove any debris and then snap thedoor shut again.

Although FIG. 1 shows collection pipe (24) perfectly straight, vertical,and central, it is actually preferable that both pipe (24) and float(21) within it are very flexible and can accommodate quite a small bendradius. This is achieved by using a thin walled pipe—typically of anelastic polymer. This allows collection pipe (24) and the float (21)within it to be inserted into downpipe (1) even when the bottom edge ofdownpipe (1) is only a few inches above the ground (2)—or where there isa ninety degree bend at the bottom of the pipe. In this case, collectionpipe (24) and float (21) will meander slightly as they are pushed updownpipe (1). The walls of downpipe (1) will support flexible innercollection pipe (24), which will remain substantially vertical as itsnakes its way upwards.

Constraining float (21) within the limited space at the top ofcollection pipe (24) ensures that cord (20) cannot become tangled andthat there is little to no scope for float (21) to become trapped—evenwhere collection pipe (24) is not perfectly straight and vertical.

Similarly, to allow the invention to be used inside non-vertical pipes,it is important that float (21) is able to rise and fall inside thesection at the end of collection pipe (24) when this is at, say, 45degrees to the vertical. To avoid float (21) sticking inside collectiontube (24), the latter should be smooth on the inside and the materialsof float (21) and collection tube (24) should be selected for minimumfriction.

Note that in the case of a non vertical downpipe (1) the “barbs” shownin FIG. 3 also serve to hold the surface of collection tube (24)slightly off the lower wall of downpipe (1) on which it would otherwiserest. This again helps to stop water running down downpipe (1) fromentering collection tube (24) until the column of water held inside thedownpipe rises to the level at which the perforations start (8).

The upward force provided by the buoyancy of float (21) when fullysubmerged must exceed the weight of valve (16), column (17), cord (20)and clip (32) by at least as much force as is pushing down on the valvedue to the column of water above it. Thus the weight of thesecomponents, the area of valve (16) and overflow height (6) determine theminimum volume of float (21) and hence an appropriate diameter ofcollection pipe (24).

Note that clip (32) allows the effective length of cord (20) to beadjusted from outside without having to dismantle the device. Whendownpipe (1) is empty of water, having positioned the appropriate lengthof collection pipe (24) above collar (25), clip (32) can be slid up ordown cord (20) so that cord (20) is just taut when valve (16) is firmlyseated. Any vertical movement of float (21) will then immediately liftvalve (16). Similarly, the height of collection pipe (24) can beadjusted by pulling or pushing inlet pipe (4) through flexible flange(23). This allows the point at which valve (16) opens to be adjusted sothat it does so when the water level in butt (5) is at required maximumlevel (6).

The tiny hole in valve (16) through which cord (20) passes also servesto let the water within downpipe (1) drip away slowly over the space ofseveral hours. This effectively resets the “first flush” mechanism asthe bottom of downpipe (1) will then have to refill to the first flushlevel (8) before water again flows into collection pipe (24) and hencevia transfer pipe (4) to water butt (5). Where this hole is left open inthis manner, it is essential to either install some form of backflowprevention such as valve (10) or to connect transfer pipe (4) to aninlet just below overflow level (6) to avoid the contents of water butt(5) slowly leaking away though this hole.

Often, such downpipes (1) have a ninety-degree bend at the bottom todirect water away from the wall to which they are affixed. In othercases the pipe is directly above a drain opening (3) and water dropsstraight down through the end. In cases where the bend at the bottom isnot easily removed or it is important that any water leaving this enddoes so at exactly the same point as it did with the bend present, avariant of the design can be used.

Where a downpipe has a vertical open face rather than the horizontalopen face shown in FIG. 1, it will be appreciated that vertically risingcheck valve (16) and associated guide rod (17) and cylinder (18) couldbe replaced by a flapper valve slightly angled from the vertical andhinged at the top so as to fall shut under its own weight. In this casecord (20) would be attached to the lower edge of the valve, pulling itopen as float (21) rises.

FIG. 3 shows a simpler approach that achieves the same goals but withoutany moving parts. This is therefore more reliable than the previousversion but has slightly lower peak flow rate under overflow conditions.

In this approach, two hollow pipes—overflow pipe (33), and collectionpipe (34)—are pushed up inside downpipe (1) and held in place by a bung(35). Although not shown in FIG. 3, the two pipes may be strapped ortied loosely together at intervals so as to keep them substantiallyparallel and to avoid either doubling back on itself as they are pushedup downpipe (1).

Bung (35) is a deformable, slightly tapered bung (narrower at the topedge) typically made of a soft waterproof, deformable material (e.g.neoprene, rubber or silicone). A plan view of an example bung is shownin FIG. 4. The thicker, central section (36) thins towards the topallowing it to be easily inserted into the downpipe and pushed up toform a tight fit. Holes (37) and (38) are of slightly smaller diameterthan pipes (33), (34) respectively that fit into them so as to form awatertight seal around the pipes. Optionally, a rigid collar may beprovided around these holes and/or a rigid insert provided within thepipes to as to strengthen them at the point they pass through thebung—allowing a tight seal to be achieved without crushing the pipes.Pinhole (41) allows water to dribble away very slowly, emptying thechamber formed at the bottom of downpipe (1) between rain showers.

Downpipe (1) is pushed down into a groove (39) to form a seal when thebung is in place. In this example, eight flaps (40) of thinner material,each of width approximately equal to one eighth of the circumference ofthe downpipe (1) can be folded up once the bung is in place so as tocompletely surround the bottom end of the downpipe (1). A jubilee clip(42) or similar is tightened around the outside of the eight flaps (40)that now surround the bottom of the downpipe (1). This is preferablytightened by a butterfly nut (43)—allowing the bung to be fitted andsubsequently removed easily, without the need for tools, for cleaning,adjusting or to be moved to another downpipe. The length of the twopipes (33), (34) can be altered independently by pulling them throughholes (37), (38) and any debris that has accumulated above the bung canbe removed—with much of it simply dropping down as the bung is released.

Alternatively, the bung may be held in place using a metal cage that isthen tightened around the end of the downpipe (1) a few inches above theopening. This is much the same principle as is used to hold a champagnecork in a bottle using a wire cage.

Note that refinements to the design of the bung allow for optimisationof the cost of materials and for a single bung design to be adapted to avariety of downpipe cross sections. The former is achieved by making thebung largely of a cheaper, rigid plastic with thinner rings ofdeformable rubber around these rigid elements. The latter can beachieved by manufacturing a single bung as a series of concentricshapes, each almost but not quite cut away from the one inside it. Theouter shape fits the largest downpipe profile supported. To use it insmaller downpipes, the installer tears off the outer ring or segmentsreducing the size to that of the next smallest downpipe profile. Where acircular and square profile overlap, four segments can be removed todrop from circular to square profile. In all cases, the bung (35)provides a snug fit inside the downpipe (1)—in much the way that atapered cork can be pushed into the neck of a bottle.

To facilitate the insertion of the pipes (33), (34), the bung (35) maybe made in two halves or hinged at one edge. This allows the bung (35)to be clamped around the two pipes with the pipes projecting through thebung (35) and hence up the downpipe (1) to whatever height is desired.The remainder of the pipes protrudes from the bottom of the bung (35)once fitted.

Collection pipe (34) is sealed at the top with a slightly overhangingcap (44)—so as to prevent water falling down the downpipe (1) fromentering it directly. The top section, above the first flush level (8)is typically 10 to 30 cm in length and is perforated as describedpreviously with relation to FIG. 2 or has larger gaps in the walls whichare then covered with a fine mesh filter. Either approach allows waterto enter easily from the sides but blocks all but the finest debris fromentering. The lower section of pipe, below the first flush level (8) issolid and watertight hence the height of the bottom edge of theperforated section above the top of the bung multiplied by thecross-sectional area of the downpipe (1) minus those of the pipes (33),(34) determines the volume of water that must accumulate in the bottomof the downpipe (1) before any flows to the water butt (5) which isconnected to transfer pipe (4), again via one-way valve (10), so as toallow water to flow into the butt (5) but not out of it.

Overflow pipe (33) is typically of larger diameter than the collectionpipe (34). There is a trade-off between peak overflow rate and firstflush volume. A larger overflow pipe (33) improves the former butreduces the latter. This pipe (33) is also sealed with an overhangingcap (45) at the top and has a perforated section immediately below thiscap. Again, water falling downwards does not enter significantly. Inthis case the perforations are typically vertical slits 75 mm tall andat least 10 mm wide. This makes the top section (46) of this pipe moreof an open cage structure—deliberately allowing debris in the water toflow through the holes without blocking them. This allows any floatingdebris—such as fresh leaves—to flush out of the system whenever itoverflows. The height of the bottom of this section of pipe above groundlevel determines the maximum height of the water column that canaccumulate inside the downpipe (1) before any excess overflows straightdown the overflow pipe (33) and into the drain (3) beneath the downpipe(1). This height should therefore be set to match the maximum fill level(6) of the water butt (5). This ensures that the water column in thedownpipe (1) can never push water through pipe (4) if the butt isalready full.

Note that in this design, it is immaterial whether the end of thedownpipe (1) is vertical, horizontal or any angle in between. The bung(35) simply fits in the end of the downpipe (1) and, if the overflowpipe (33) is cut off as it exits the bung, any water exiting it does soin the same direction it would have done in the absence of theapparatus. Alternatively, the open end (47) of the overflow pipe (33)can be directed down into the drain (3) allowing subsequent adjustmentsto be made to the overflow level (6): increasing it by pushing theoverflow pipe higher or reducing it by pulling the pipe downwards thenretightening the bung around the downpipe (1).

A variant on this design is shown in FIG. 5. Rather than pushing twoseparate pipes (33), (34) of different lengths up the downpipe (1), asingle, larger diameter pipe is used (48). This is divided internallyinto two chambers that provide the same functions as the two separatepipes of FIG. 3. With fewer parts and a more streamlined shape, it iseasier to insert this assembly into the downpipe (1) and to position thebung (35) around it. The overflow grille (50) can be larger while thefilter-covered or perforated area at the top of the collection chamberwithin the tube extends around at least part of the outside of thecombined tube.

Although the invention has, thus far, been described as an add-on to anexisting downpipe (1) it will be appreciated that the entire mechanismcan be built into a downpipe section, thus avoiding the need for the“boot” (11) or bung (35) to be clamped on to the bottom of the otherwiseopen pipe. An example of this is shown in vertical cross section in FIG.6, and horizontal section through the lower section (just below thefirst flush level (8)) in FIG. 7. In this approach, the lower end of thedownpipe is moulded or extruded to provide the overflow channel (48) andopening (51) and pinhole for first flush reset (52) in the otherwisesealed accumulation chamber (53). Collection of water for the water butt(5) is via small holes or filter mesh (49) between the first flush level(8) and overflow level (6) as before but now in a built-in channel downone side of the downpipe (1). Alternatively, rather than dividing thepipe as shown in FIG. 7, a concentric design with central collectioncolumn and annular overflow pipe or other geometric designs can be used.

As in the earlier figures, it will be appreciated that the transfer pipe(4) to the water butt (5) may be a continuation of the collection pipeor chamber inside the downpipe (1) or there may be a connector providedat the bottom of the downpipe allowing the pipes to be of differentdiameter and/or construction. Transfer pipe (4) is typically garden hosewhile that inside the downpipe is preferably a more flexible,thin-walled pipe which is easily bent as needed when inserting it.

In the case of a built-in unit as in FIG. 6, the option of removing thebung (35) to clean the collection area is not available. A hingedsection at the bottom of the pipe with a push fit catch—similar to thatdescribed earlier with respect to the boot (11) of FIG. 1-would allowsimple snap-open adjustment and cleaning.

For a downpipe section as shown in FIG. 6, the peak flow rate understorm conditions is not as great as it would have been for anunencumbered flow through the downpipe. In further variants, therefore,the cross-section of the pipe can be increased to provide largerfirst-flush collection volumes and/or to provide an overflow exit (51)of the same size as the original downpipe—with the collection pipe andaccumulation areas being accommodated within this extra cross-sectionalarea. This results in a slightly wider section at the bottom of adownpipe.

Unlike the add-on solutions of the earlier Figures, the overflow height(6) of the apparatus shown in FIG. 6 cannot be adjusted simply byraising or lowering an overflow pipe. Instead, the walls of the internaldividers could contain punch-outs allowing the overflow level to be setbefore the bottom section of downpipe is connected. Alternatively, astrip of plastic pushed up through a guide could progressively cover theholes in the overflow section (50) and hence by pulling this out fromthe bottom of the pipe, the height of the lowest exposed overflow holecould be adjusted.

In all the previous examples, note that the use of a non-return valve(10) is only required if the bottom of the downpipe is not watertightand where the transfer pipe (4) attaches to the water butt below thefill level (6). There is thus a trade-off between having an automatictrickle release reset on the first flush collector and the need for anon-return valve. If the trickle release (provided by the pinhole in thecenter of the valve (16) of FIG. 1; the pinhole (41) in the bung ofFIGS. 3, 4 and 5 or the pinhole (52) in the bottom of the collectionchamber of FIG. 6) is blocked, then the water level in the bottom of thedownpipe (1) and the water butt (5) will equalise and there is no needfor valve (10). A refinement to the design is therefore to mould thebung (35) or downpipe section so that the holes (41) and (52) are notopened unless they are deliberately punched out or the end of projectingnipple is cut off.

As the invention relies on maintaining a column of water slightly higherthan the water level in the water butt(s) that it feeds, it is importantthat the downpipe (1) is reasonably watertight. Where a non-return valve(10) is used, slight dripping is unimportant as long as the volumeescaping is very much less than that flowing to the water butts.However, in some cases, it may be appropriate to seal a leaking jointwithin the lower section of the downpipe (1). A compressible rubber orplastic ring may be placed around the joint and compressed around itwith a jubilee clip to form a substantially watertight seal. It will beappreciated that there are many alternative approaches to sealing,caulking or otherwise blocking such leaks.

An alternative to the deformable bung of FIG. 4 is to use an inflatablecollar. This avoids the need for flaps (40) and external fixationdevices such as the jubilee clip (42) and butterfly nut (43). Such anapproach is much less visible as the whole of the inflatable collar canbe pushed up inside the downpipe (1) and inflated, gripping the pipe(s)going through it and the inside of the downpipe wall. All that is thenvisible outside the downpipe is the transfer pipe (4) taking the waterto the water butt (5). This approach is ideal for historic buildingswhere attachments to the downpipes would detract from the appearance ofthe property.

The inflatable collar, being (when deflated) much smaller than thecross-section of the pipe, can be designed to grip the collection pipe(34) much further up—at the bottom of the perforated section ifrequired. It can then be inserted up to the appropriate height andinflated well inside the downpipe (1). Although this reduces the firstflush volume, it significantly reduces the length of overflow pipe (33)required since this does not need to project below the collar, merely topass through it. As the overflow pipe is the bulkiest item in thedesign, this provides a more compact and material efficient design.

The very nature of such inflatable collars means that a single collardesign can accommodate a range of downpipe sizes and shapes. Metric andimperial sized domestic downpipes differ in size by a few millimeters.Square, circular and rectangular downpipes all exist. A suitableflexible collar will fill the inside of any of these shapes as it isinflated.

Further refinements to the design include measures to make it easier toinsert the collection and/or overflow pipes. Rounded edges and lowfriction material on the tops of the pipes help to stop them catching oninternal obstructions or joints as they are pushed up the pipe.

A concern on very tall downpipes is that, should the downpipe (1)completely fill with water in a storm, the force acting down on the boot(11), bung (35), or inflatable collar at the bottom of the pipe may pushit out. This can be countered by extending the overflow pipe (33)upwards with a watertight (and hence airtight) section between the topof the grille (46) and overhanging cap (45). Even if the water columninside the downpipe rises above the top of the grille (46) an airchamber is maintained in this top section of the overflow pipe. Thisprovides up-thrust due to Archimedes principle and pulls the pipe (33)upwards—reducing the net downward force on the bung (35). The ratio ofthe cross-sectional area of the overflow pipe to that of the downpipe asa whole determines the net effect of additional water in the pipe.

An alternative approach to connecting the apparatus to the water butt(5) can be taken—in which the transfer pipe (4) is connected to an inletat the overflow level (6) of the water butt. This may be done via theoverflow outlet (7). In this case, water would not flow up the transferpipe (4) and into the butt (5) until the column of water inside thedownpipe (1) reaches the height (6) of the said inlet (7). The advantageis that, without any requirement for a valve (10), the water butt (5)cannot empty through the transfer pipe (4) even if the apparatus isremoved for cleaning or the chamber at the bottom of the downpipe (1) isotherwise not watertight. Note that the porous/perforated section of thecollection pipe does not need to be at this height. It can remain lowerbut the water will still not flow until the head of water above itreaches the new level (6) at which the transfer pipe enters the waterbutt (5).

In this configuration, the initial “first flush” volume of water thatmust flow down the downpipe (1) before the barrel starts to fill issignificantly greater than when transfer pipe (4) connects to the base(9) of the water butt (5). This can be offset by the apparatuses ofFIGS. 3, 4 and 6 deliberately having a very wide overflow pipe (33), orsection of pipe (48). This restricts the cross-sectional area of thechamber, which must fill before flow to the water butt starts. Underextreme flow conditions (typically summer storms) this approach providesa lower flow rate to the butt (5) as the head of water above the inletlevel must be restricted more than in the case where the transfer pipe(4) enters low (9). With the transfer pipe (4) connected to overflowoutlet (7) the butt (5) will overflow either through a further, slightlyhigher hole or over the lip of the butt. In either case there istypically only a few centimeters between these levels. There is nothingto stop the traditional approach of an overflow pipe being taken fromthis higher level in the water butt (5) to an appropriate drain orsoak-away but if it is important to cope with excess water in thedownpipe, the overflow mechanism within the apparatus must be adjustedto operate between these levels. There is therefore a maximum of a fewinches of head pushing water into the water butt (5). Note, however,that this is no worse than the case with prior art apparatus insertedinto the downpipe at this level. These typically have a collectionchamber only a few centimeters deep and hence have similarly restrictedpeak flow rates.

The skilled person will be aware of a range of possible modifications ofthe various embodiments described above. Accordingly, the presentinvention is defined by the claims and their equivalents.

What is claimed is:
 1. An apparatus for the collection of water flowingdown a substantially watertight pipe, comprising: a substantiallywatertight bung or boot through which at least one duct passes; whereinthe bung or boot is affixed to a lower end of a substantially verticalwatertight pipe thus forming a substantially watertight chamber from asubstantially upper surface of the bung or boot and the existing wallsof the watertight pipe without significantly increasing the resultanttotal length of the watertight pipe; and wherein the apparatus isfurther characterized in that at least one of the ducts projects upwardswithin the watertight pipe so as to allow passage of water through aplurality of raised collection holes at a predetermined height withinthe watertight chamber to a water collection tank or vessel.
 2. Theapparatus of claim 1, wherein accumulated water is allowed to leak awayslowly through an orifice in the bottom of the watertight chamber so asto force a further volume of water to be collected before water againflows to the collection chamber.
 3. The apparatus of claim 1, whereinthe plurality of raised collection holes are each arranged beneath anoverhanging projection that serves to prevent water from fallingvertically down the watertight pipe after entering the duct via thecollection holes.
 4. The apparatus of claim 1 in which the accumulatedwater level is constrained from rising above a pre-determined level byproviding an overflow path through which excess water flows once thepre-determined level has been reached.
 5. The apparatus of claim 4,wherein the overflow mechanism is a valve in a wall of the watertightchamber.
 6. The apparatus of claim 5 wherein the valve is opened bymeans of a float lifted as the water level in the watertight chamberrises above a threshold level.
 7. The apparatus of claim 4 wherein theoverflow mechanism is provided by one or more openings beginning at thepre-determined level being in communication with the outside of thewatertight pipe.
 8. The apparatus of claim 7 wherein the openings are inthe walls of the watertight pipe.
 9. The apparatus of claim 7 whereinthe openings are in a further duct within the watertight pipe.
 10. Theapparatus of claim 1 wherein the seal is achieved by means of adeformable bung or boot inserted into the lower end of the watertightpipe.
 11. The apparatus of claim 1 wherein the seal is achieved by meansof an inflatable collar inside the lower end of the watertight pipe. 12.The apparatus of claim 10 wherein the bung or boot is fabricated tofacilitate the removal of one or more sections of the bung or boot so asto allow it to fit within a range of cross-sectional sizes and/or shapesof the watertight pipe.
 13. The apparatus of claim 6 wherein the floatis constrained within the upper portion of the duct containing thecollection holes.
 14. The apparatus of claim 4 wherein separate internalducts respectively transport water to the collecting tank and providethe overflow path.
 15. The apparatus of claim 14 wherein the internalducts are joined together to facilitate insertion into the watertightpipe.
 16. The apparatus of claim 7 wherein the internal ducts share acommon wall for at least a portion of their perimeter.
 17. The apparatusof claim 1 wherein access to the watertight chamber is facilitated byway of an opening in the lower section of the watertight chamber. 18.The apparatus of claim 17 wherein the access is by way of a hinged flap.19. The apparatus of claim 17 wherein the access is by way of aremovable section of wall of the watertight pipe.
 20. The apparatus ofclaim 1 wherein the connection between the watertight chamber and thecollection tank is made at or above the required fill level of thecollection tank.
 21. The apparatus of claim 1 wherein the seal isachieved by means of an inflatable collar placed completely within thewatertight pipe.